A traditional silver-based jewelry alloy is comprised of sterling silver, which ordinarily contains 92.5% silver and the balance of the composition includes one or more base metals, typically including copper. In general, silver-based alloys with lower silver content show higher tarnish rates as compared with traditional sterling silver jewelry and therefore have not been used for jewelry making. Further, such low silver content alloys typically have issues of cost, such as the cost of alternative metals, as well as issues associated with tarnish avoidance, hardness, formability, and durability.
The recently rising cost of precious metals including silver has impacted the jewelry industry and has led to evolving markets for alternative alloys that contain low or no precious metals, and that retain the benefits of color, tarnish resistance, hardness, formability, and durability. Specifically, there is demand for low silver containing alloys that are tarnish resistant, can be used for jewelry making, and which may exhibit particular colors, such as but not limited to the traditional jewelry alloy colors of pink, yellow and green. These colors may be in different shades as well, such as different shades of pink, including pale shades.
Some work on developing low silver containing alloys has been done in the past, such as low silver containing alloys for jewelry contain 20%-25% silver by weight (w %), which are mixed with zinc, copper, and nickel. Depending on the material mix, such alloys may appear in a pastel color, such as pink, green or yellow. However, the tarnish resistance of these alloys is compromised because of the low silver and high copper content.
As a result, there is a need in the jewelry industry for a variety of low silver containing alloys which individually display a particular color and also demonstrate improved performance with respect to formability as well as improved resistance to tarnish.